Thalestris24

Hi Ken In my case, the slit takes up the width of the guide cam fov - think I posted an image some time ago. I'll have another look at it today. I don't think the SharpCap reticule is moveable, unfortunately but I'll double check that and maybe try Firecapture also. I have the bits to add slit illumination Thanks Louise

Hi Ken Along DEC rather than RA? I suppose that makes sense, and the AVX has a lot of DEC backlash. I've never used an oag before. Until I try, I won't know what's visible in the guide cam. My Travel Scope is 70mm x 400mm and that's what I'd use for plate solving - not the internal guide image. SharpCap has a 'reticule' option and supports plate solving. I'm not sure if the reticule is the same as Firecapture's overlay. I don't understand about setting an 'offset crosswire'. Plate solving is my only practical way of finding a target - I normally use it with SharpCap or APT, but it's only accurate up to a point. It won't necessarily get a star precisely in the centre of the fov but is always good enough for a DSO. I bought an Altair Astro GPCAM3 178m to use on the Travel Scope a couple of months ago. Not even properly tried it yet! It should give a smallish fov of ~1 deg x 0.70 deg at full fov though supports ROI. I'll need the plate solving in order to know what's visible in the Travelscope/178M fov. I've never really used an overlay before either - nor the PHD 2 slit overlay, obv. Lots to try out! Thanks Louise

I'm thinking ahead a little and wondering what my procedure would be for getting a particular star in position on the slit? I'd planned to use plate solving via a separate guide scope (Celestron Travel Scope 70) but I'm not totally convinced that will be accurate enough. However, I can't see another way of doing it. If I can identify the selected star in the fov of the Lowspec guide camera then I think could make any necessary fine adjustments via PHD2. I'm also wondering how I'll manage to keep the target star over the slit when my guiding is only +/- 4 arc secs on the AVX - it might be ok but I'm not sure how to convert arc secs to microns (I should know but my brain has gone to sleep!). The practicalities of using a slit spectrometer are still a bit unknown to me at the moment! I gather from Ken's book (ASA) using a flip mirror and aligning the slit in RA is the way to go. The latter is fine but a flip mirror won't work for me. So it looks like platesolving of easily identifiable stars is all I can do. At the moment my Travel Scope is fixed rigidly to the scope clamps. I'll need to be able to adjust it so that I can get its centre of fov to precisely align with that of the imaging scope (or near enough). I'll have to think about how best to do that - I suppose guide rings are probably the way forward. Louise

Hiya Not really. I reprinted the slit illuminator with Paul's new version. Also enlarged the hole in guide platform rather than printing the new version. Yet to test it. Have printed a small box for the 12V inverter. I'm waiting for some panel mounted 12V sockets and new soldering bit - hope they come tomorrow. That's about it, really. Cheers Louise

Paul - have you received your 150W inverters yet? I think they are also small but, as you say, *overkill... I did clip off the diodes on my board but it looks like they are generally being sold without them on Ebay Cheaper from China but quicker from UK Louise ps a 1W inverter would do! But then you have to make your own.

Here is Sylvania 70W starter and the neon: It's not as bright as the neon to my old phone camera! But should be fine. I've no idea how long these bulbs last. The ones I just bought had a blackened inside out of the box. But they are pretty cheap - cost me £1.50 for 5. I suppose they are not meant to run continuously for any length of time. Every make/bulb is different. As I mentioned before, the non-reclosure voltage (Below that threshold the bulb shouldn't close it's contacts) for the Sylvania 70W starter bulbs is 140V so I calculated the resistor based on a more conservative 130V and 4mA. A problem is that the characteristics of the bulbs aren't defined for our purposes but I'm sure we can muddle through! Oh, I found yesterday that you can get starter bulbs for 125W systems and with a non-reclosure voltage > 150V. I might get some and try them, just for fun! But I really should get on and finish the Lowspec now and get it mounted and tested. Louise

You can get them very cheap off Ebay - as little as £1.50 from China. You can also get them without the diodes that provide the unwanted DC output (I think I'll clip off the diodes on my board). Unfortunately, despite my initial belief, there doesn't seem to be a 110V tapping after all . It doesn't really matter - just seems marginally safer at 110V (it could be very easy to pick up the bare board forgetting the 12V is connected.. Zap! Ouch! So really need a box for it). They are supposed to supply up to 40W - so at 220V that would be a current of about 0.2A.I don't know what the 12V side draws - not much with little load on the secondary side. But I think a starter only draws about 3-4mA, so less than 1W. I calculate a 22.5K resistor will allow up to 4mA to pass so that would dissipate 0.36W. I'm assuming a Sylvania 70W starter which has a non-reclosure voltage of 140V and running it at 130V. I'll try that in a minute It should be quite bright... Should be virtually no heating from the inverter board. I think that '150W' board you ordered is also quite small? It does have the advantage of different output tappings (as I've seen online) Louise.

A quick test of the 12V/40W cheap, Chinese DC to 220VAC inverter: It works ok with a 12V battery and a neon - yay! You can see from the image of the board where I've sketched the position of the diodes which look like they give a DC output at B. 220V AC is between A and C. There is a 267V DC voltage between A and B - so care is needed! It doesn't look like a standard digital multimeter picks up the AC output which I suppose is high frequency - not a 50Hz sine wave! That means the inverter is really only good for things like lighting. Also, one shouldn't assume the inverter isn't working if you do use just a multimeter to check it. There is an AC voltage between A and 1 which lights a neon. There is a higher AC voltage between A and 2 which lights a neon very brightly! It could be that the voltage between A and 1 is 110V AC. I'll try a starter bulb with a resistor between those to points . Just to mention, the inverter is 40mm square and 25mm high so only needs a small box to put it in - I need to try and seek one out... Anybody know a source of inexpensive small, plastic boxes? The price of ABS ones I've seen is a bit out of proportion to the size and value of the inverter! Louise

I'll do a new calibration when I can Thanks Louise

Oh, ok. I just zoomed right in on what otherwise looks like a narrow peak on the full chart: 739 this time! Louise

Oh, ok. I'm still learning BASS... I did another reading on the same chart and it came out at 859 - maybe I'm not doing it properly! Louise

Hi Paul No worries! I guess it is that causing the shadows above? I thought I'd get away with ignoring it but it obviously affects the BASS chart. Reprinting the guide platform would be a bit of a pain. Would just enlarging the hole version a bit more be good enough? Any idea why my R value (above) is only 594 - not sure if the theoretical value (Simspec) takes into account the ccd properties? Cheers Louise ps I had enlarged the openings with a file - I suppose not quite enough....

My measured R-value is 594 which seems quite low though my pixels are quite big (5.4um). The theoretical value with a 20um slit is 1906. Quite a big discrepancy? Wavelength range seems fairly close, theoretical: 3785 - 7215 (3430 A), so a little less than that in practice. Louise

I changed the Ovio slit disk holder to the Lowspec 3 version. I've not changed the Ovio guide platform or slit illuminator though. However I did file them the best I could. I also reposition the Sylvania starter bulb a little - it was a little low down compared to the S10 bulb. Anyway, the result was a brighter image without changing the resistor . But.. the spectrum seems to have shifted to the right (in the red direction). I'm not sure why/how that's happened as I've not touched the micrometer which has been in the same position for a while now. I'm wondering if a slight change of direction of the source illumination could have resulted in spectrum shift? Although the calibration will have changed I've still used the original S10 anyway this time though I'll obviously have to redo it. On the plus side, the blue end peaks are much better now and more like I'd envisioned . If I can identify the wavelengths then it could be a better calibration bulb than the S10. I received the wee 12v inverter today. It really is very small. No instructions with it though the +/- 12V inputs are marked and I have the 220/240V AC outputs from online. It only has a total of 8 components, plus 4 diodes for optional DC output, so it should be easy to draw/reverse engineer the circuit and work out 110V AC transformer tappings . Will try and do that in the next day or two. I've also come across references to it being able to run from voltages much lower than 12V so will investigate that as well. ps I meant to mention that I'd noticed some shadow top and bottom of the exposure. I'm assuming that will be due to the holes in the slit platform and slit illuminator not being quite big enough? I'll maybe reprint the slit illuminator at some point but I don't really want to take the slit platform apart again if I can get away with it. Louise

Thanks - it is very frustrating. I'm likely to call it a day in a year or so and will try and sell all my kit. Louise

I'm close to a city centre in a 2nd floor apartment

If I change units to Angstrom it prints Wavelength (A) correctly but puts an extra zero in the values i.e. 410nm shows as 41000 rather than 4100?

Um, anyone know why the BASS chart x scale is Angstroms but the label says nm? Is it me or a bug? Thanks Louise

Yes, I do and I do. I've not had occasion to print any .75 pitch threads since the Lowspec - apart from the updated Ovio slit holder which I've printed but not fitted yet. Cheers Louise

Hi Peter Well I've not actually used either in a long time... Main problem with the AVX has been the backlash. I'm always hampered whatever I do because I'm limited to imaging through an open window. Hope you enjoy using yours! Louise

I have this 115mm scope as well and have it on an AVX which is not the best mount for it. I have fitted a usb autofocuser, also from TS. It's a lovely scope, but, being a triplet, it can take a while to temperature stabilise (depending on storage/ambient temperatures). I've not actually used it in a while but have been thinking of attaching the Lowspec spectrometer to it. I've not yet completely finished commissioning the spectrometer but it shouldn't be too long before I'll be ready to try it. Louise

Thanks for that Paul I found an xml for a t2/m42 and m48 thread a while back but it disappeared before I got around to trying it . I still have the file. You'd think Autodesk would make life easier for users... I've done my best to calibrate the Ender 3 Pro now though I'm still sceptical about its ability to print threads. Anyone know if I can get Cura to slice at 0.1 rather than the 0.12 it seems to insist on? Would it make a difference anyway? Louise

Yeah, I bought 10 of the S10 bulbs! Plus 5 of the Sylvania ones. A bulb should last quite long time - as long as a neon bulb under similar conditions. I just tried out the Sylvania bulb. It wasn't so bright, unfortunately and disappointingly, though that was with a 33k resistor. Since the bulbs can run at ~150V without closing, then a smaller resistor should allow a greater current / higher voltage across the bulb. It should then be brighter. I'll have a look to see if I have a suitable resistor I've not received the Chinese 12V input power supply yet. I mistakenly mentioned before that you could run a glow bulb from 110V without a resistor but actually you still need a current limiting resistor in series otherwise the bulb will pass a relatively high current if the source can deliver it. As that will likely be in the amps range with a 40W-rated supply, the bulb will glow bright but not last very long - at all! It will probably blow up - not good! In general, the greater the current the shorter the bulb life. I'll try the Sylvania bulb via the 240V mains again but with a 18k-22k resistor and see how it behaves. Here is spectrum at 120s exposure: And chart with S10: There are plenty of peaks at the blue end - just mostly a bit small! Louise

I bought some Sylvania brand 70W starters from the local Toolstation this morning - their last box of 5 for £1.50 . They have a quoted non-reclosure voltage of >150V. I believe they give off light more in the blue end of the spectrum but I'll have to test one to be sure. Still, here's a grab from the youtube video I saw one on: Looks pretty blue-violet there! Could be mostly argon and/or mercury. Probably rich in UV so best not to stare at it... I did find that you can get so-called 'spectrum tubes' of single gases for ~£15 each but they are like 26cm long and need a special, expensive eht (1000-5000V) power supply (though I daresay one could put a diy one together). Louise

Oh ok, that's reassuring - thanks! I'm sure I'll be ok to keep the files I have anyway. I'm pretty sure I have backups of all my important files on an external hdd but I'll double check my backups are up to date Louise